GFCIs are to prevent electrocution, AFCIs are to prevent fire. The first probably has way less false alarms and is way easier to troubleshoot but Siemens has a gadget you can rent to debug AFCI problems. You may have more AFCI problems if you live near a transmitting tower.

I doubt anyone has done a cost/risk/benefit tradeoff analysis for US use of these. The countries that use RCDs may be more forthcoming with this type of info.

Thanks, under what conditions do i need to use either or both? My electrician used afci's for the outside lights, sump pump and outdoor receptacles. I saw some GFCI's in the kitchen, but not next to the sink which is where i thought they would go. Why are some GFCI and some are not?

An upstream GFCI may protect downstream kitchen outlets but the outlets should be marked.
To check protection push the test button on the GFCI and see if the outlets go dead.
IMHO, a better way to check the whole circuit is to put a 7-1/2w bulb between the hot and ground on the questionable outlets and listen for a click from the GFCI.

Thanks Guys, i don't need to test them per say. I had to re-wire a bunch of circuts and was swapping out breakers. One of the breakers that needed to be replaced was a combination AFCI, i went to the box store and to an AFCI. I just wanted to make sure i got the right thing for the job.

I don't know the code and i wanted to know when i have to use a GFCI or when to use an AFCI. From the sounds of it, the AFCI won't do the job, i either need a GFCI or Combo like what was there previously. To be honest, i didn't realize it until i read the side of the breaker i removed. i saw AFCI but i failed to see the combo above it.

For future reference, when do i need to protect against electrocution and when do i need to protect against fire? Thanks

For future reference, when do i need to protect against electrocution and when do i need to protect against fire? Thanks

Electrocution and fire danger from electricity are pretty low in the US but wet skin and current passing through your chest (like if you are standing in water on a grounded concrete floor) raises your odds of serious injury.

The biggest shock I ever got as a kid was standing barefoot on concrete and touching probably 700vdc from an ancient tube radio set. I was trying to force an auto radio vibrator into a four prong tube socket.
At this voltage the wet skin doesn't matter because the skin is punctured.